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authorSergei Petrunia <psergey@askmonty.org>2020-02-05 00:54:16 +0300
committerSergei Petrunia <psergey@askmonty.org>2020-02-05 00:54:16 +0300
commitb3ded21922fc684c3c1aeb4ad57161bc2fec5859 (patch)
tree4e3a7c8268dc62a878e0c4229a04aad2358873d1
parentb0fa30808622fe12d474a70af1838906e60b9897 (diff)
downloadmariadb-git-b3ded21922fc684c3c1aeb4ad57161bc2fec5859.tar.gz
ha_partition: add comments, comment out unused member variables
-rw-r--r--sql/ha_partition.cc2
-rw-r--r--sql/ha_partition.h91
2 files changed, 90 insertions, 3 deletions
diff --git a/sql/ha_partition.cc b/sql/ha_partition.cc
index a7942f493d7..130c7f7e4d5 100644
--- a/sql/ha_partition.cc
+++ b/sql/ha_partition.cc
@@ -6235,7 +6235,7 @@ static range_seq_t partition_multi_range_key_init(void *init_params,
ha_partition *partition= hld->partition;
uint i= hld->part_id;
DBUG_ENTER("partition_multi_range_key_init");
- partition->m_mrr_range_init_flags= flags;
+ // not used: partition->m_mrr_range_init_flags= flags;
hld->partition_part_key_multi_range= partition->m_part_mrr_range_first[i];
DBUG_RETURN(init_params);
}
diff --git a/sql/ha_partition.h b/sql/ha_partition.h
index 1085eca72cc..fc6c8c4d570 100644
--- a/sql/ha_partition.h
+++ b/sql/ha_partition.h
@@ -184,17 +184,61 @@ private:
bool is_subpart);
};
+
+/*
+ List of ranges to be scanned by ha_partition's MRR implementation
+
+ This object is
+ - A KEY_MULTI_RANGE structure (the MRR range)
+ - Storage for the range endpoints that the KEY_MULTI_RANGE has pointers to
+ - list of such ranges (connected through the "next" pointer).
+*/
+
typedef struct st_partition_key_multi_range
{
+ /*
+ Number of the range. The ranges are numbered in the order RANGE_SEQ_IF has
+ emitted them, starting from 1. The numbering in used by ordered MRR scans.
+ */
uint id;
uchar *key[2];
+ /*
+ Sizes of allocated memory in key[]. These may be larger then the actual
+ values as this structure is reused across MRR scans
+ */
uint length[2];
+
+ /*
+ The range.
+ key_multi_range.ptr is a pointer to the this PARTITION_KEY_MULTI_RANGE
+ object
+ */
KEY_MULTI_RANGE key_multi_range;
+
+ // Range id from the SQL layer
range_id_t ptr;
+
+ // The next element in the list of MRR ranges.
st_partition_key_multi_range *next;
} PARTITION_KEY_MULTI_RANGE;
+/*
+ List of ranges to be scanned in a certain [sub]partition.
+
+ The idea is that there's a list of ranges to be scanned in the table
+ (formed by PARTITION_KEY_MULTI_RANGE structures),
+ and for each [sub]partition, we only need to scan a subset of that list.
+
+ PKMR1 --> PKMR2 --> PKMR3 -->... // list of PARTITION_KEY_MULTI_RANGE
+ ^ ^
+ | |
+ PPKMR1 ----------> PPKMR2 -->... // list of PARTITION_PART_KEY_MULTI_RANGE
+
+ This way, per-partition lists of PARTITION_PART_KEY_MULTI_RANGE have pointers
+ to the elements of the global list of PARTITION_KEY_MULTI_RANGE.
+*/
+
typedef struct st_partition_part_key_multi_range
{
PARTITION_KEY_MULTI_RANGE *partition_key_multi_range;
@@ -203,10 +247,23 @@ typedef struct st_partition_part_key_multi_range
class ha_partition;
+
+/*
+ The structure holding information about range sequence to be used with one
+ partition.
+ (pointer to this is used as seq_init_param for RANGE_SEQ_IF structure when
+ invoking MRR for an individual partition)
+*/
+
typedef struct st_partition_part_key_multi_range_hld
{
+ /* Owner object */
ha_partition *partition;
+
+ // id of the the partition this structure is for
uint32 part_id;
+
+ // Current range we're iterating through.
PARTITION_PART_KEY_MULTI_RANGE *partition_part_key_multi_range;
} PARTITION_PART_KEY_MULTI_RANGE_HLD;
@@ -810,21 +867,51 @@ public:
uint m_mrr_new_full_buffer_size;
MY_BITMAP m_mrr_used_partitions;
uint *m_stock_range_seq;
- uint m_current_range_seq;
+ // not used: uint m_current_range_seq;
+
+ // Value of mrr_mode passed to ha_partition::multi_range_read_init
uint m_mrr_mode;
+
+ // Value of n_ranges passed to ha_partition::multi_range_read_init
uint m_mrr_n_ranges;
+
+ /*
+ Ordered MRR mode: m_range_info[N] has the range_id of the last record that
+ we've got from partition N.
+ */
range_id_t *m_range_info;
+
+ // TRUE <=> This ha_partition::multi_range_read_next() call is the first one
bool m_multi_range_read_first;
- uint m_mrr_range_init_flags;
+ // not used: uint m_mrr_range_init_flags;
+
+ /* Number of elements in the list pointed by m_mrr_range_first. Not used */
uint m_mrr_range_length;
+
+ // Linked list of ranges to scan
PARTITION_KEY_MULTI_RANGE *m_mrr_range_first;
PARTITION_KEY_MULTI_RANGE *m_mrr_range_current;
+
+ /*
+ For each partition: number of ranges MRR scan will scan in the partition
+ */
uint *m_part_mrr_range_length;
+
+ /*
+ For each partition: List of ranges to scan in this partition.
+ */
PARTITION_PART_KEY_MULTI_RANGE **m_part_mrr_range_first;
PARTITION_PART_KEY_MULTI_RANGE **m_part_mrr_range_current;
PARTITION_PART_KEY_MULTI_RANGE_HLD *m_partition_part_key_multi_range_hld;
+
+ /*
+ Sequence of ranges to be scanned (TODO: why not stores this in
+ handler::mrr_{iter,funcs}?)
+ */
range_seq_t m_seq;
RANGE_SEQ_IF *m_seq_if;
+
+ // Range iterator structure to be supplied to partitions
RANGE_SEQ_IF m_part_seq_if;
virtual int multi_range_key_create_key(